That’s not true though right? Don’t grocery stores buy the products that are on their shelves and they are reselling them? That’s fundamentally different from a marketplace.

No, not usually. Usually the seller pays the grocery to carry items, and the seller owns the items until sold.

For some products the seller even stocks the items on the shelves.

That said, what brands got that special treatment was very much decided by Publix, so they were still curating the selection, they just weren't paying up-front for the goods or responsible for keeping those shelves looking good.

They definitely owned the product, while it was on their shelves.

Even if a vendor has a buyback guarantee for expired product, if someone were to break in and steal all the product, its the store who is liable not the vendor.

That was the original point I was arguing against.

My point is that grocery store is not a good analogy because Amazon is not the same as a retail store, they are a combination store and marketplace.

To be fair, I think I would be more comfortable comparing Amazon to Sears in it's heyday.

I'm sure that exists, but it's not common. Grocery stores often charge slotting fees, but that's not the same as renting shelf space--the store still owns the product (even if there is an agreement to buy it back if it doesn't sell).

Also retail stores take on more product liability than marketplaces like flea markets do.

In the case of items actually run through the register, I'm not sure how that's dealt with from an accounting standpoint. I do know that the stores have the ability to return 100% of unsold goods in those cases.